As the use of digital data increases, the demand for faster, smaller, and more efficient memory structures used for storing that digital data increases. One type of memory structure which has recently been developed is a crossbar memory structure. A crossbar memory structure includes a set of upper parallel wires which intersect a set of lower parallel wires. A programmable memory element is placed at the intersections between the upper and lower parallel lines. The programmable memory element may store digital data.
One type of programmable memory element which may be used is a memristive element. A memristive element is a device which changes the state of its resistance based on an applied programming condition. For example, a programming condition may be applied to change the memristive element from a high resistive state to a low resistive state or vice versa. A high resistive state may represent a digital “1” and a low resistive state may represent a digital “0”.
One challenge that results from use of a crossbar memory structure is the process of reading the state of a specific memory element. The state of a memory element may be determined by applying a sensing condition such as a sense voltage or a sense electric current. The behavior of the sensing condition when applied to a memory element may be indicative of the current state of that memory element. However, when applying sensing conditions in such a manner, the sensing condition will be adversely affected by other memory elements along the upper wire and along the lower wire to which the memory element to be read is connected. Thus, it is difficult to isolate the memory element to be read from other memory elements within the crossbar array for the purpose of reading the state of the memory element.
Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements.